Various products of interest, such as biofuels like fatty acid esters or alcohols, functional foods, vitamins, pharmaceuticals such as lactams, peptides and polyketides or terpenes and terpenoids and also biopolymers such as polyhydroxyalkanoates can be produced via genetically enhanced cyanobacteria. Genes for the production of these valuable compounds can, for example, be put under the control of an inducible promoter so that the cyanobacterial cells can grow in an uninduced state, accumulating biomass and after induction produce the compound of interest. One of these valuable compounds is ethanol. In this context, the PCT patent application WO 2009/098089 A2 discloses the use of ethanologenic genes, for example pyruvate decarboxylase and alcohol dehydrogenase for the production of ethanol. High ethanol production rates can be obtained by bringing these genes under the transcriptional control of the promoter from the petJ gene which is induced by copper deprivation and repressed by addition of at least 1.5 μM copper to the growth medium of the cyanobacteria. Therefore this promoter requires dilution of the medium in order to induce the culture, which is hard to achieve during the continuous process of culturing the cyanobacteria. Therefore, there is a need for improved inducible promoters for the transcriptional control of genes for the production of first chemical compounds.
This task is solved by providing a genetically enhanced cyanobacterium as described herein.